| 摘要 |
PURPOSE:To improve the interrupting performance by providing a metal spacer, partly coated with an inorganic insulating material, between the main electrode and the coil electrode and eliminating a leakage current flowing through the spacer and generating a sufficient longitudinal magnetic field. CONSTITUTION:A spacer 5 is formed by coating an inorganic insulating material 6 such as ceramics on the surface of a metal cylinder 5a made of stainless steel, etc. There are various coating methods, but the alumina ceramics coating by plasma jet melting method is most suitable from the viewpoint of manufacturing processes. To assemble a vacuum valve, silver soldering at a high ambient temperature of 800-900 deg.C is required, but as a plasma coated film has air holes, even if there is a large difference in thermal expansion coefficient the air holes absorb and relax the stress, so that the peeling of the film will never occur. Owing to the insulating performance of the spacer 5, the total interrupting current flows through the coil electrode 2 and a strong longitudinal magnetic field is applied between the electrodes to improve the interrupting performance and moreover an electrode structure with a high mechanical strength can be obtained. |
